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将对应模块的Servlet写入到一个指定的模块中,模块化编程
使用switch方式
package com.qf.servlet;
import java.io.IOException;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.Arrays;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;import sun.rmi.transport.proxy.HttpReceiveSocket;
/**
* Servlet implementation class EmpServlet
*/
@WebServlet("/emp/*")
public class EmpServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
/**
* @see HttpServlet#HttpServlet()
*/
public EmpServlet() {
super();
// TODO Auto-generated constructor stub
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// 请求的url
String requestURL = request.getRequestURL().toString();
System.out.println(requestURL);
String[] split = requestURL.split("/");
// System.out.println(Arrays.toString(split));
// 获取到需要执行得Servlet方法
String method = split[split.length-1];
switch (method) {
case "insert":
insert(request,response);
break;
case "delete":
delete(request,response);
break;
default:
return;
}
}
public void delete(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
System.out.println("我是删除方法");
}
public void insert(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
System.out.println("我是添加方法");
}
/**
* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
*/
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
doGet(request, response);
}
}
使用反射
@WebServlet("/dept/*")
public class DeptServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
public DeptServlet() {
super();
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
String requestURL = request.getRequestURL().toString();
String[] split = requestURL.split("/");
String method = split[split.length-1];
// 当前类对象
Class<? extends DeptServlet> clazz = this.getClass();
// 获取当前对象的方法
try {
// 获取需要执行的方法
Method declaredMethod = clazz.getDeclaredMethod(method, HttpServletRequest.class,HttpServletResponse.class);
// 启动暴力反射
declaredMethod.setAccessible(true);
// 方法的反向执行
declaredMethod.invoke(this, request, response);
} catch (Exception e) {
System.out.println("没有对应的方法");
}
}
public void insert(HttpServletRequest request,HttpServletResponse response) throws ServletException, IOException {
System.out.println("添加方法");
}
private void delete(HttpServletRequest request,HttpServletResponse response) throws ServletException, IOException {
System.out.println("删除方法");
}
private void update(HttpServletRequest request,HttpServletResponse response) throws ServletException, IOException {
System.out.println("修改方法");
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
doGet(request, response);
}
}
异步的JS与XML技术,可以实现JS和服务器之间的异步交互
异步交互:在不刷新网页的前提下,局部代码与服务器进行交互
AJAX不是新技术,也不是编程语言,就是一个使用JS和后端进行交互的技术
AJAX的优点:用户体验非常好;缺点:开发改错困难,不可回退
场景1:AJAX验证用户名是否重复
package com.qf.servlet;
import java.io.IOException;
import java.util.ArrayList;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* Servlet implementation class CheckNameServlet
*/
@WebServlet("/check")
public class CheckNameServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
public CheckNameServlet() {
super();
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
String name = request.getParameter("name");
// 模拟从数据库中获取数据
ArrayList<String> list = new ArrayList<>();
list.add("张三");
list.add("李四");
list.add("王五");
list.add("tom");
list.add("jack");
list.add("rose");
// 何如判断name在list中
boolean contains = list.contains(name);
// false是可用 true是不可用
// System.out.println(contains);
// 0不可用 1可用
response.getWriter().print(contains?0:1);
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
doGet(request, response);
}
}
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title></title>
</head>
<body>
<input type="text" id="username">
<span id="msg"></span>
<script>
window.onload = function(){
let username = document.querySelector("#username");
let msg = document.querySelector("#msg");
username.onblur = function(){
// 发送ajax请求
// 1.创建AJAX对象
let xhr = new XMLHttpRequest();
// 2.封装AJAX的请求数据(形式为:xxxxServlet?xxxx=xxxx&xxx=xxx)
xhr.open("GET","check?name="+username.value);
// 3.发送请求
xhr.send();
// 4.AJAX的请求状态判断
// readyState
// 0:ajax创建但未初始化
// 1:ajax创建完成但未发送请求
// 2:ajax发送请求到服务器端
// 3:ajax请求正在被处理
// 4:ajax请求处理完成,可以使用ajax获取服务器响应的数据
xhr.onreadystatechange = function(){
if(xhr.status == 200 && xhr.readyState == 4){
// 5.获取响应的数据
let result = xhr.responseText;
if(result == 0){
msg.innerHTML = '用户名已存在';
msg.style.color = 'red';
}else{
msg.innerHTML = '√';
msg.style.color = 'green';
}
}
}
}
}
</script>
</body>
</html>
配合AJAX进行分离式开发中，数据的交互形式之一
JSON可以实现不同系统,不同语言之间的数据交互
JSON是一种数据格式,类似于JS中的{}对象
语法:
??{
???“key”:“value”,
???“key”:“value”,
???…
??}
数据体量小,可以做为数据传入的载体
使用第三方工具(jar、依赖)
Gson
?谷歌发布
Jackson
?Springn内置的
FastJson
?阿里发布的
package com.qf.test;
import java.util.ArrayList;
import java.util.HashMap;
import org.junit.Test;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.google.gson.Gson;
public class TestJSON {
@Test
public void test01() {
System.out.println("helloworld");
}
@Test
public void test02() {
Gson gson = new Gson();
String json = gson.toJson("helloworld");
System.out.println(json);
}
@Test
public void test03() {
Gson gson = new Gson();
String json = gson.toJson(new Dog(1,"李四"));
System.out.println(json);
}
@Test
public void test04() {
ArrayList<Dog> dogs = new ArrayList<>();
dogs.add(new Dog(1,"1"));
dogs.add(new Dog(2,"2"));
dogs.add(new Dog(3,"3"));
dogs.add(new Dog(4,"4"));
String json = new Gson().toJson(dogs);
System.out.println(json);
}
@Test
public void test05() {
ArrayList<Dog> dogs = new ArrayList<>();
dogs.add(new Dog(1,"1"));
dogs.add(new Dog(2,"2"));
dogs.add(new Dog(3,"3"));
dogs.add(new Dog(4,"4"));
int currPage = 10;
HashMap<String,Object> map = new HashMap<>();
map.put("dogs", dogs);
map.put("page", currPage);
String json = new Gson().toJson(map);
System.out.println(json);
}
@Test
public void test06() throws Exception {
Dog dog = new Dog(1,"1");
ObjectMapper objectMapper = new ObjectMapper();
String json = objectMapper.writeValueAsString(dog);
System.out.println(json);
}
}